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Moon Phases With Bisectors
Draw a line across the terminator (the light/dark edge) and a line from the Moon to the Sun. The horns of a crescent point away from the Sun.
Yellow: direction to the Sun · Blue: terminator bisector
Before you start
A line through the terminator and a line toward the Sun explain the crescent ‘horns’.
Key idea
The horns of a crescent point away from the Sun. The terminator is the day/night line on the Moon.
What you see
- Moon disk
- Sun direction (yellow)
- Terminator bisector (blue)
Try this
- Waxing crescent vs waning crescent
- Notice light on the right vs left
Common mistakes
- Drawing the crescent pointing at the Sun
Glossary
- Terminator
- Boundary between lunar day and night.